Human-Centered Webcasting of Interactive-Whiteboard Lectures

In our system for recording and transmitting lectures over the Internet, the board content is transmitted as vector graphics, producing thus a high quality image, while the video of the lecturer is sent as a separate stream. It is easy for the viewer to read the board but the lecturer appears in a separate window. As a result, two areas of the screen are competing for the viewer´s attention, causing the widely known split attention effect. To eliminate this problem, the lecturer is extracted from the video stream and his or her image is pasted onto the board image at video stream rates. The lecturer can be dimmed from opaque to semitransparent, or even transparent. The article presents a detailed analysis of the underlying psychological problems and explains the multimedia techniques that are applied to achieve the solution